1. Field of the Invention
The present invention relates to an IEEE 802.15.3 high-speed wireless personal area network (WPAN) using an ultra-wide band (UWB), and more particularly to a high-speed WPAN which can support communications among devices included in different piconets in the high-speed WPAN.
2. Description of the Related Art
A wireless communication technique using UWB is a technique that guarantees a transmission distance in the range of 10 m to 1 km. The UWB wireless communication technique had been used as a military wireless communication technique by the US Department of Defense for the past 40 years, and has been open to the nonmilitary sector by the Federal Communications Commission (FCC), which is the US authority on communication frequencies.
The UWB wireless communication technique is a ultrahigh-speed wireless data transmitting technique using a bandwidth of several GHz, for high transmitting speed (of 500 Mbps to 1 Gbps) with a low power consumption ( 1/100 of the power consumption of a mobile phone or a wireless LAN) in comparison to other existing transmission techniques, such as IEEE 802.11, Bluetooth, etc. The UWB wireless communication technique can be used in diverse fields such as a short-distance personal communication network that connects a computer, peripheral devices and home appliances to an ultrahigh-speed wireless interface in a short distance (up to 100 m), a radar for examining, by fluoroscopy, the interior of a building, a high-precision position measurement, a device for preventing a car collision, an underground mine detector, a system for preventing the loss of an article, or a detection of an object inside a body, etc.
A standard for the UWB wireless communication technique has been proposed as a high-speed wireless personal area network (WPAN) in IEEE 802.15.3. In the IEEE 802 standards groups, IEEE 802.15.1 is a group that establishes the Bluetooth standards, and IEEE 802.11 is a group that establishes the wireless LAN standards.
Bluetooth has been commercialized as a widely known personal area network (PAN), and has recently been applied to many network-related products. Bluetooth generally uses a frequency band of 2.4 GHz (i.e., ISM band), and provides a personal area network (PAN) solution with its communication distance limited to less than 10 m. The wireless LAN of the IEEE 802.11 group that takes charge of the wireless LAN standard has already been standardized.
IEEE 802.15.3 has be divided into three task groups; TG1 (Task Group 1), TG2 and TG3. TG1 establishes the Bluetooth standards, and TG2 performs technical analysis of methods for enabling Bluetooth products and existing wireless LAN business to coexist. TG3 researches the standard of a high data rate PAN solution, and is now conducting research in a transmission system having transmission speeds of more than 55 Mbps.
FIG. 1 illustrates an exemplary piconet designated among communication devices in an IEEE 802.15.3 high-speed wireless PAN. As shown the piconet that forms the high-speed wireless PAN is composed of a plurality of communication devices 10, 12, 14, 16 and 18. One device 10 among them operates as a piconet coordinator (PNC). Here, the PNC serves as a master of the corresponding piconet and performs synchronization with the respective devices, manages time slots for data communication, and performs other control operations.
PNC device 10 manages the time slots required for the communications among the devices located in the piconet by using a message referred to as a beacon in order to perform synchronization with the connected devices 12, 14, 16 and 18. PNC 10 additionally serves to control a QoS (Quality of Signal), a power save mode, and piconet access.
As described above, the IEEE 802.15.3 device 10, serving as the piconet coordinator, can designate the piconet. The device having a capability as the piconet coordinator forms the piconet by searching
channels in order to start the piconet, selecting one of the channels that is not in use, and broadcasts a beacon frame through the selected channel. The devices 12, 14, 16 and 18 that have received the broadcast beacon frame set the channel for their communications in response to the received beacon frame. In this case, the PNC device 10 allocates and provides IDs for the respective devices 12, 14, 16 and 18 that have responded to the beacon.
In another aspect, a device may take part in the piconet already formed, through an association procedure. That is, the device, which has moved from the outside onto the already formed piconet A, requests connection with a device in the piconet A . Accordingly, PNC device 10 provides a single device ID to the device that has requested the connection., which can be used in the piconet A.
Through the above-described process, the piconet as shown in FIG. 1 is formed. Here, the respective devices 12, 14, 16 and 18, except for the PNC device 10, request PNC device 10 for data transmission. The PNC device 10 allocates communicable time slots to the respective devices 12, 14, 16 and 18 in response to the data transmission request. When the PNC device 10 allocates the time slots to the respective devices 12, 14, 16 and 18, it uses the beacon frame. The respective devices 12, 14, 16 and 18 perform the data transmission in a time corresponding to the time slot allocated by the PNC device 10.
When a device desires to terminate the communication in the piconet or to perform a disconnection, a piconet disassociation procedure is performed between the PNC device 10 and the corresponding device. In this case, the PNC device 10 deletes information about the recorded device through the piconet disassociation procedure.
The piconet designated between the PNC device 10 and the respective devices 12, 14, 16 and 18 may be divided into an independent piconet which can independently allocate the time slots to the devices existing in the piconet, and a dependent piconet which distributes and allocates the time slots provided from a PNC device located outside the piconet to the devices existing in the piconet. If a dependent piconet is newly produced in a independent piconet, the independent piconet at that time is referred to as a parent piconet, and the newly produced dependent piconet is referred to as a child piconet or a neighbor piconet. In this case, the independent piconet becomes the parent piconet, and the dependent piconet becomes the child piconet. In this case, the child piconet (i.e., dependent piconet) shares and uses the channel provided from the PNC device of the parent piconet.
FIG. 2 is a view illustrating an example of a dependent piconet designated in the IEEE 802.15.3 high-speed wireless PAN network.
According to FIG. 2, the existing piconet is a parent piconet 30, and a PNC device of the parent piconet 30 is referred to as P-PNC device 32. A device having a capability of being a PNC device, except for the P-PNC device 32, among the devices 22, 32 and 42, which constitute the parent piconet 30, can be defined as child piconet 20 (C-PNC).
P-PNC device 32c, located in the parent piconet 30, allocates time slots to the C-PNC device 22 and another device 34, which define the child piconet, and transmits the beacon frame. Here, the C-PNC device 22 is a device that performs a PNC function in the child piconet 20.
C-PNC device 22 may also define the child piconet 20, and separately manage and control the device 24 that is included in child piconet 20. The communication in the child piconet 20 can be performed only between the devices 22 and 24 that define the child piconet 20.
Accordingly, the C-PNC device 22 is a member that is included in the parent piconet 30 and manages and controls the child piconet 20. Thus, the C-PNC device 22 can perform a communication with the devices 32 and 34 in the parent piconet 30.
However, in the conventional IEEE 802.15.3 high-speed wireless PAN using the ultra-wide band (UWB), it is impossible to perform a communication between the device 34 in the parent piconet 30 and the device 24 in the child piconet 24. This results in inefficient communication between devices of different networks. Hence, there is a need in the industry for a method and system for communicating between devices of different networks